Here's another thing.
Every time I make an appearance, or sit on a panel with other authors, we invariably are asked to talk about our writing processes -- the wheres, whens, and hows.
In fact, recently, another author who was sitting on a panel with me called me insane. I like that. I do my best writing before 6 AM. It's hard to explain it, but at that time of day, when I've just woken up and have a cup of coffee with me, and everyone is totally asleep, the words just kind of write themselves. Many times, I'll write things that I totally didn't foresee writing at all, and then I'll look back on those words later on in the day and think, damn, where did this come from?
I can write in the afternoon, too, but around 4 PM is the cutoff. At 4 PM the words are a struggle and I feel like I really have to try to get content out. 4 PM is only good for spell-checking and editing stuff that I've done earlier in the day.
I know a lot of writers who write at night. I even know one who closes himself behind a curtain like the Wizard of Oz.
Me... I like 3 AM.